So my current daily driver is a jk wrangler that is modified in today jeep ways with larger tires, lift, etc. It's fun in it's own way and it's off road capabilities far surpass what I'm even comfortable trying. But I keep having this dumb thought rolling through my mind, what if you built a Wrangler that was very focused for autocross in the scca cam class. I know it would never truly match a well built and driven modern pony car but I think it could be a fun challenge.Hear me out here!
So the Wrangler has several really obvious disadvantages; weight, stick axles, really high center of gravity, and not a huge amount of power.
But what about advantages? Number one would definitely have to be the ability to easily fit any of the largest 200twr autocross tires on the market under the stock fenders. Next most interesting thing about this build would be just how much weight could actually be jettisoned. According to the internet, a basic two door Wrangler weighs around 4000-4200 pounds depending on trim etc. I believe you could easily drop about 500 pounds off with just basic stuff. And honestly I think getting it into the low 3000s is definitely possible. For reference look at the Jeep "stitch" concept where jeep engineers got a jk down to about 3000 pounds with aggressive weight loss techniques. They even replaced exterior sheet metal with architectural fabric, sort like a light aircraft. This concept still had a fully functioning 4wd system in too, which is something an autocross car definitely wouldn't need. I would definitely on removing the front driveshaft, stripping the front axle of its shafts and differential, and even removing the transfer case. Removing the front drive also gives the opportunity to boost up the caster as well and even bend the tubes or inner C's for more camber. But really there are just too many weight loss opportunities to list. All that weight loss and the factory 285 hp would basically put it into the power/weight ratio of something like a 350z!
The engine coupled with a light flywheel and the six speed manual would be really fun and peppy, especially if it was hauling around 1000 pounds less than it used to!
Final drive ratios are basically available in whatever number you want and you can even get factory LSDs. Also a basic sport model with 3.21 gearing and typical autocross tire diameter will give you a near 60mph redline speed in second, perfect for most courses.
I'm my opinion, suspension and steering would really be the biggest hurdle. Obviously you would want to lower the thing as much as possible. Unfortunately, this would probably require notching the frame to clear the drag link and front panhard bar to get the car suitably low. I think you would ultimately be looking for 3-5 inches of lowering to get the cg suitably low. The factory steering box sucks and I don't really know a way around that. You'd probably also have to look into custom shocks/springs/coilovers. The circle track market could be pretty helpful here.
I'm sure I've missed some points here but if I think of them I'll be sure to post them. So what do you guys think? Honestly I think there's a lot of hidden performance potential in this platform that has never been explored because it's so antithetical to it's typical purpose. Plus you'd get to piss off a lot of jeep guys!
There are e-mod and d-mod "jeeps" that occasionally make an appearance. They are more tube frame vehicles with jeep grills than jeeps though.
I think a Philippines style owner-type jeep with independent front suspension could be fun in whatever class it was legal while remaining street legal.
ojannen said:
There are e-mod and d-mod "jeeps" that occasionally make an appearance. They are more tube frame vehicles with jeep grills than jeeps though.
I think a Philippines style owner-type jeep with independent front suspension could be fun in whatever class it was legal while remaining street legal.
I have seen those tube frame jeep style autocross cars before and that's really not what I'd be going for. Yes, what I'm thinking of would definitely be stripped out and spartan, but it would still be pretty streetable and usable as a car.
I think the thing that really makes this all possible is just how loose the cam class ruleset is. It would really let you take control of just how much useless weight there is on a jk and allow you to get rid of it all.
I will mention that if you read the scca solo rulebook the Wrangler is actively explicitly prohibited in the cam class (and I think actually all classes) and this is probably due to rollover risk. But I believe a suitably lowered and modified Wrangler would be safe and meet the height to width ratio. I also believe that most local regions really wouldn't care as long as it looks stable. I have no plans to go to Nats so the rulebook exclusion is kind of a moot point to me.
freetors said:
I'm my opinion, suspension and steering would really be the biggest hurdle. Obviously you would want to lower the thing as much as possible. Unfortunately, this would probably require notching the frame to clear the drag link and front panhard bar to get the car suitably low. I think you would ultimately be looking for 3-5 inches of lowering to get the cg suitably low. The factory steering box sucks and I don't really know a way around that. You'd probably also have to look into custom shocks/springs/coilovers. The circle track market could be pretty helpful here.
A stock wrangler is 20+ inches higher than most factory stuff that's decent at autox. I think you'd be looking to lower a lot more than 3-5 inches. You would need to come down 10" minimum just to get it legal to run from a rollover standpoint.
I think the GRM Challenge Cherokee is great and all but I am curious how that compares to a car you'd find on the local autox course. This is why I like seeing non-challenge cars run for comparison (but they didn't back then).
What 200TW tires are you thinking you would run? I have trouble believing you could fit enough to overcome the other problems.
Personally, I'd put in a m2 front with a rack.
Rear would be axle over spring and a c notch for suspension clearance.
You could easily be to a 3" overall height clearance.
Jeep made those 2WD DJ5's for the post office workers to deliver the mail. Getting it low enough will be a challenge.
Good luck - I'll be watching.
Datsun310Guy said:
Jeep made those 2WD DJ5's for the post office workers to deliver the mail. Getting it low enough will be a challenge.
Good luck - I'll be watching.
It's been a while since I've read the actual letter of rulebook regarding the stability criteria but I believe it came down to basically needing to be wider than it is tall. If that's the case my current jeep with a 2.5" lift and 35s is already 79" wide at the outside of the tires and 74" tall. The 315 and 335 autocross tires on the market would always account for lowering it a good amount and widening the vehicle too.
To be perfectly clear, I don't know that I would ever actually do this. Yes I think it would be a lot of fun. But even the most basic used jeeps are pretty expensive nowadays. And I'm sure making it into an autocross car would pretty much ruin any value it would have.
STM317
PowerDork
1/22/23 5:38 p.m.
Every couple of months, I see a lowered JKU with a V8 swap and chromed 5 spoke 18s on my commute. It's always had the hard top on it I think.
No idea what V8 was swapped in, or what was done to lower it though.
For what it's worth, a semi modern minitruck would have all of the same advantages as the Wrangler, while having better front suspension, better steering, and a bed to haul spares.
parker
HalfDork
1/22/23 5:44 p.m.
You can, but why? Throwing a ton of money and work into something that will perform worse than a bone stock $5000 Miata. If you want to do it for laughs go for it.
This makes me think of the Comanche race trucks that the Archer Brothers (?) raced in the late 80s..
NickD
MegaDork
1/22/23 6:29 p.m.
I had a friend that autocrossed a ZJ Grand Cherokee 5.9L. Tires with a low-profile sidewall dropped it quite a bit, and then he had two F-350 Super Duty front coil springs (way higher rate and the right diameter) that he cut in half and installed front and rear. He used offset ball joints to get more front camber.
It was really funny, but it wasn't competitive, at all. The steering rate was waaaay to slow, the seats don't hold you in place at all, and the spring rates were too high, particularly in the rear. It was legal for autocross but every tech guy gave him a hassle over it.
In reply to parker :
Why does Rice play Texas...
Not because they are easy, but because they are hard.
freetors said:
Datsun310Guy said:
Jeep made those 2WD DJ5's for the post office workers to deliver the mail. Getting it low enough will be a challenge.
Good luck - I'll be watching.
It's been a while since I've read the actual letter of rulebook regarding the stability criteria but I believe it came down to basically needing to be wider than it is tall.
Track width must be wider than height. So subtract your tire width from above and yeah, you are still way tall. The published SSF value for a wrangler is a pathetic 1.09 (2017 and 2020). 1.30 is required to be eligible for autox (street class). Pretty much the only listed vehicles I could find that are worse are a couple of full size trucks and Ford Transit vans.
I keep getting the idea of taking a Wrangler, throwing the frame away, building strut towers front and rear, and putting an independent suspension in it, to use as an autocross kinda car.
Working on basically doing that to the Mini has absolved me of this desire. I'd still like to see it done, though. You could get the things really low if you didn't need the front axle to have to clear the oil pan.
Pete. (l33t FS) said:
I keep getting the idea of taking a Wrangler, throwing the frame away, building strut towers front and rear, and putting an independent suspension in it, to use as an autocross kinda car.
I want to do similar with a Cherokee. I want a streetable fun to drive RWD utility box that is at normal sedan height.
ProDarwin said:
Pete. (l33t FS) said:
I keep getting the idea of taking a Wrangler, throwing the frame away, building strut towers front and rear, and putting an independent suspension in it, to use as an autocross kinda car.
I want to do similar with a Cherokee. I want a streetable fun to drive RWD utility box that is at normal sedan height.
Don't you want 4 wheel drive? With low profile tires? My Volvo was handicapped into the modified class back in the 80's and I could keep up with the C4 Corvettes time wise, but got slaughtered by the handicap and could never come close with the Honda CRX's or Rabbits driving around on 3 tires. It didn't matter, I was only racing against myself and having a blast doing it. 
A 2-by makes it easier, you can run a drop axle to clear the oil pan.
I was going to suggest an IH Scout (F&R solid axles on link+coilover suspension, AWD transfercase, body-drop).
But here is more proof for an automotive equivalent to 'Rule 34' (every possible modification to a vehicle has already been done... and most already mentioned on GRM)
The past CAM rules specifically disallowed all jeep wranglers. The "improved" 2023 rules have dropped that line, not sure if that's an oversight or a purposeful change.
Racebrick said:
ProDarwin said:
Pete. (l33t FS) said:
I keep getting the idea of taking a Wrangler, throwing the frame away, building strut towers front and rear, and putting an independent suspension in it, to use as an autocross kinda car.
I want to do similar with a Cherokee. I want a streetable fun to drive RWD utility box that is at normal sedan height.
Sounds like a Volvo 240.
It's not far off, except the Cherokee is about 2 feet shorter
When I've thought about a 'race' Wrangler before, in my mind it looks something like these:
.
Unfortunately, the reality is that it would probably end up up looking more like these:
.
Don't get me wrong, I actually don't hate them... But an autox machine they are not. Much like the race Cherokee, the bottom of the body is still over a foot off the ground at axle centerline. Even if you wanted to go lower, and could modify the frame and suspension to accommodate, the fenders don't look to be as readily accommodating as one might expect. So while you might be able to build something lowered enough to 'have fun' with it, and maybe even turn a few surprised heads at how much better it does than expected, but I don't see any way to give a reasonably stockish bodied Wrangler actual performance handling. Now if we're talking about effectively tube framing it and taking great liberties with the body, then you start looking more like this again...
Pete. (l33t FS) said:
I keep getting the idea of taking a Wrangler, throwing the frame away, building strut towers front and rear, and putting an independent suspension in it, to use as an autocross kinda car.
Working on basically doing that to the Mini has absolved me of this desire. I'd still like to see it done, though. You could get the things really low if you didn't need the front axle to have to clear the oil pan.
The solution to oil pan clearance is often to find a 2wd front axle (2wd JKs existed for the first couple years of the model, for a TJ you'd use a 2wd XJ/ZJ axle). Then you can notch the axle for more oil pan clearance.
